1. Field of the Invention
This invention relates to loading apparatuses of the type comprising an outer boom and an extension boom (telescopic boom) telescopically extendable in the outer boom as well as at least one hydraulic line which extends with a flexible elastic portion from the outer boom to the telescopic boom in a sufficiently large bight-forming loop to permit maximum extension of the telescopic boom in relation to the outer boom.
2. Description of the Prior Art
Hydraulic lines extending from an outer boom past or via an extension boom in said outer boom to for instance operating cylinders for a grapple or like loading implement carried at the outer end of the extension boom always prove difficult to arrange in a simple manner and at the same time in such way that the lines are well protected and can be extended and retracted without being damaged at the retraction and extension movements of the telescopic boom.
A common type of loader in which problems of this kind often occurs is the two section knuckle boom. To permit increasing the reach of the boom system the outer boom is usually made extendable by means of an extension boom or telescopic boom, in which case the grapple or like loading implement is carried at the outer end of the telescopic boom. The first section of the boom and the outer boom as well as the telescopic boom are usually box beams. A hydraulic cylinder mounted within the first boom section and the telescopic boom usually serves as means for extending and retracting the telescopic boom (which may be divided into several telescoping sections). The hydraulic lines to be connected to said cylinder extend from the first boom section usually externally past the joint between the first boom section and the outer boom and run into said outer boom, but in addition the hydraulic lines must extend from the outer boom to the lifting implement carried by the telescopic boom. The last-mentioned hydraulic lines must be of a length permitting maximum extension of the telescopic boom. When the telescopic boom is retracted these lines consequently are too long and form bights.
In this type of knuckle booms the problem of running the hydraulic lines has been solved in many different ways. In the simplest solutions, flexible hydraulic hoses extend from the outer boom beneath the telescopic boom and via the front end of said telescopic boom to the loading implement. Upon retraction of the telescopic boom said hoses are allowed to place themselves in entirely deliberate depending bights with the ensuing risk that they will obstruct operation and may easily be damaged. More complex and expensive arrangements include protective pipes and guides for flexible hose sections or telescopically extendable pipes which are exposed to wear and give rise to sealing problems.
It may seem obvious to place the hydraulic lines well protected within or without the first boom section and the outer boom since it is prior art and conventional to place the hydraulic lines protected within the first boom section and also within the outer boom when said outer boom is not telescopically extendable. However, it is by far simpler to arrange hydraulic lines in a well protected location in knuckle boom systems having boom sections of constant length than in telescopically extendable boom sections, and so far no solution has been suggested, that can be considered satisfactory in view of both the requirement for simplicity and low cost and the requirement for protection against damage and wear.